An image forming apparatus such as an MFP (Multi-Function Peripheral) has a plurality of components and a plurality of consumable items. The physical property of each component changes depending on a use status each component. The same applies to the physical property of a consumable item.
A transfer apparatus is an example of a component of an MFP. The transfer apparatus includes a transfer roller pair. Recently, a conductive sponge rubber roller pair is mainly used as a transfer roller pair. Even if the transfer roller pair operates in a normal situation, the electric resistance of the transfer roller pair increases as the use time period increases. Finally, the transfer bias reaches the transformer permissible voltage maximum value, and the transfer roller pair cannot apply a current necessary to transfer and reaches the end of the lifetime. As described above, even if the transfer roller pair operates in a normal situation, the transfer roller pair reaches the end of the lifetime as the electric resistance increases.
Meanwhile, even before the transfer roller pair reaches the end of the lifetime in a normal operational situation, the electric resistance of the transfer roller pair may increase if a failure occurs in a component of the transfer apparatus. If the transfer roller pair itself is broken or a power source is broken, the transfer roller pair cannot transfer paper normally. Further, if a bearing of the transfer roller pair is broken, the transfer roller pair cannot come to close contact with a transfer belt.
When the transfer roller pair reaches the end of the lifetime in a normal operational situation, it is necessary to replace the transfer roller pair. The MFP cannot execute printing until a service person replaces the transfer roller pair. So, if it is possible to predict the lifetime of the transfer roller pair, the MFP may execute an action for reducing downtime in advance such as output of an alert or execute a life-prolonging action, with which it is possible to use the MFP for a while after the transfer roller pair reaches the end of the lifetime.
Meanwhile, if any failure occurs in the transfer apparatus, a component of the transfer apparatus may be about to be broken critically. In view of that, if it is possible to determine whether or not there is a failure in a component of the transfer apparatus, a user may stop the operation of the MFP and call a service person.
However, even if a transfer roller pair operates in a normal situation, the electric resistance of transfer roller pair largely varies depending on a lifespan (aging or aging degree) of the transfer roller pair or a use status such as a use environment. Further, the electric resistance of the transfer roller pair largely varies also when the transfer roller pair itself is broken or a component relating to the transfer roller pair is broken. Because of that, an MFP cannot predict a lifetime of a transfer roller pair or cannot determine whether or not there is a failure in a transfer apparatus including the transfer roller pair only on a basis of the electric resistance of the transfer roller pair.